Preparation of dyed filaments and films



Patented June 2, 1936 onrrso STATES PATENT OFFICE Roland Riisch,Opladen, Austria, and Hermann Schmidt, Leverkusen-Wiesdorf, Germany,assignors to I. G. Farbenindustric Alrtiengesellschaft,Frankfort-on-the-Main, Germany No Drawing. Application December 3, 1934,

Serial No. 755,848. 1933 3 Claims.

The present invention relates to the preparation of dyed filaments andfilms, preferably to the preparation of dyed cuprammonium and viscosesilk.

Up to the present time the dyeing of artificial silk from regeneratedcellulose was usually carried out in special dye-works and not in theartificial silk works, since the dyeing process on account of itscomplicated character and the variety of methods of carrying out theprocess requires a thorough acquaintance with the art of dyeing whichthe experts of the artificial silk industry generally do not possess. Itis, there'- fore, a problem to combine the spinning and dyeing ofartificial silk in a simple manner so as to enable the manufacturers ofartificial silk to prepare dyed material without the necessity of usingcomplicated dyeing methods. It has been tried to solve this problem byincorporating dyestufis within the spinning solution, the working up ofthe latter, 1. e. precipitation, washing, rinsing, bleaching, etc. beingperformed in the usual manner. However, this process shows thedisadvantage of yielding dull shades, the yield of the dyestuff employedbeing relatively small.

It is the object of our present invention to avoid this disadvantagewithout influencing the spinning process itself. We have found thatfilaments and films prepared from artificial masses, such as regeneratedcellulose, cellulose esters and others can be dyed excellently vivid anduniform shades by incorporating within the spinning solutions serving asstarting material for the preparation of the filaments and films a vatdyestuff and subjecting the same after the preparation of the filamentsand films has been completed to a reduction process so as to form theleuco compound and to a subsequent oxidation process so as to regeneratethe dyestuff. Our new process is intended to be employed in the firstline for the preparation of artificial threads from regeneratedcellulose such as for the preparation of cuprammonium or viscose silk.In this case that vat dyestufi is suspended in the spinning solution,from which the artificial threads are prepared by projecting the sameinto the precipitating baths, the threads being then subjected to anafter treatment with a reducing agent, which is capable of vatting thedyestuff and to a subsequent treatment with an oxidizing agent, such asoxygen or air.

As reducing bath there is used in the first line an alkalinehydrosulfite bath, it being understood that other reducing agents knownto be In Germany December 6,

capable of vatting vat dyestuffs, being likewise operative in ourpresent process. The aftertreatment of the threads with reducing and.oxidizing agents is preferably effected after the preparation of thefilaments or films has been performed. Obviously, this means that thevatting and oxidizing of the vat dyestuffs can be performed at any stageof the finishing operations as soon as the thread has acquiredsufiicient strength to withstand the strain involved by the reducing andoxidizing process, and we wish it to be understood that all thesepossibilities are intended to be embraced by the term after thepreparation of the filaments and films has been performed used in theclaims.

As a matter of fact the manner of precipitating the filaments and filmsand of effecting the finishing operations is not materially changed whenworking according to our new process, Washing, rinsing, bleaching,sizing and weighting being performed in the usual manner. Furthermore,we wish to point out that our inven tion is in no way restricted to aspecial spinning and precipitating process, it being to be understoodthat it is operative in the dry-spinning and stretch-spinning processand regardless as to the nature of the precipitating bath employed.

The effect involved by our present invention lies in the fact thatshades of a much better brilliancy and a much better yield of thedyestuff are obtained than it is possible when working as described inthe preamble i. e. by merely suspending the dyestuffs in form ofpigments in the spinning solutions. Our experiments have proved thatthis is more or less true in the case of every vat dyestuff and ourinvention is in no way restricted to special dyestufis or a specialclass of vat dyestuffs.

The following examples will illustrate the invention, withoutrestricting it thereto:

EXAMPLE 1 cuprammonium silk To a 10% cuprammonium cellulose solutionthere are added (calculated on the weight of the cellulose) ofIndanthrene blue GDC double paste (Colour Index No. 1113), after pastingthe latter with water. The precipitation of the threads is performed inthe usual manner by projection through a nozzle into an acidprecipitating bath. After removal of the copper, the material is treatedat 5060 C. for half an hour in an aqueous bath containing per litre 12cos. of an aqueous solution of sodium hydroxide of 40 B. and 2-3 gramsof powdered sodium hydrosulfite. The material is then washed, oxidized,treated with a soap solution, dried and finished as usual. It is ofadvantage to add some sodium chloride to the alkaline hydrosulfite bath.The yield and brilliancy of the shades obtained in this manner is by farbetter than that of the shades obtained by mere adding the dyestuifwithout subsequent application of reducing or oxidizing agents.

Instead of the Indanthrene blue GDC, there can be used with the sameadvantage, for instance, the following dyestuffs:

Indanthrene brilliant green B (see Colour Index Suppl. p. 43)

Indanthrene red brown 5RF (see Colour Index Suppl. p. 43)

Indanthrene black BGA (see Colour Index No. 1102) Indanthrene dark blueBOA (see Colour Index No. 1099);

Indanthrene yellow 3RN (see Colour Index page 355) Indanthrene yellow3GP (see Colour Index Suppl. p. 43);

Indanthrene green GG (see Colour Index page 43).

EXAMPLE 2 Viscose silk To a 7% cellulose xanthate solution there areadded 5% (calculated on the weight of the cellulose) of Indanthrenebrilliant green B paste fine (see Colour Index Suppl. p. 43). Thesolution is then spun with the known acid baths. The threads are washedwith a weak aqueous solution of sodium carbonate and then treated at50-60 C. for half an hour in an aqueous bath containing per litre 12cos. of an aqueous solution of sodium hydroxide of 40 B. and 23 grams ofsodium hydrosulfite, in order to reduce the dyestuif of the leucocompound. The material is then washed, oxidized and finished in theusual manner. The yield and brilliancy of the shades obtained in thismanner is by far better than that of the shades obtained by mere addingthe dyestuff without subsequent application of reducing and oxidizingagents.

EXAMPLE 3 Cuprammonium silk To a cuprammonium cellulose solution of theusual composition there is added a mixture of the following dyestuffs,the mixture being intensely mixed in a suitable apparatus, for instance,a ball mill:-

5% of a dibenzanthrone paste,

7.2% of a brown dyestufi paste (obtainable, for instance in accordancewith U. S. P. 1,690,236 [dicarbazole of IA-trianthrimidel),

6% of a yellow pasted dyesuif, obtainable, for instance, by reactingwith sulfuric acid monohydrate upon 1.5-trianthrimide,

the quantities of the dyestuffs being calculated on the weight ofcellulose employed. Preferably, the dyestuffs are used in a finelydispersed form. The spinning solution thus obtained is spun into aWeakly alkaline precipitation bath. The copper is removed from thethreads by means of a 10% aqueous solution of sulfuric acid. Thematerial is then thoroughly washed out and treated at 4050 C. for onehour in an aqueous bath containing per litre 5 cos. of an aqueoussolution of sodium hydroxide of 40 B., 2 grams of sodium hydrosulfiteand 20 grams of crystallized sodium sulfate. After rapidly rinsing inwater several times, a completely homogeneous dark-brown shade isobtained.

We wish to point out that the dyestufi combination employed in thisexample would not be applicable in the usual dyeing of ready threads,films, ribbons or the like, as it would yield unequal fancy shades.

EXAMPLE 4 Viscose film To a 7% cellulose xanthate solution there areadded 5% (calculated on the weight of the cellulose) of Indanthrenebrilliant green B fine paste. The viscose solution is projected througha nozzle of about 1 metre breadth into the known acid precipitationbaths, whereby the cellulose is regenerated in form of a broad film. Thefilm is Washed with the usual acid and alkaline precipitating baths and,after removal of the impurities, treated at 50-60 C. for half an hour inan aqueous bath containing per litre 12 cos. of

an aqueous solution of sodium hydroxide of 40 B. and 2-3 grams of sodiumhydrosulfite. The film is then washed again, oxidized, washed once moreand dried on drying rollers as usual. An intensely colored film isobtained.

We claim:

1. In the process of preparing dyed filaments and films from artificialmasses such as regenerated cellulose, cellulose esters and ethers, themodification which comprises incorporating within the solution servingas starting material for the preparation of the filaments and films avat dyestuif and subjecting the same after the preparation of thefilaments and films has beenperformed to a reduction process so as toform the leuco compound and to a subsequent oxidation process so as toregenerate the dyestuff.

2. In the process of preparing dyed threads from regenerated cellulosethe modification which comprises incorporating within the solutionserving as starting material for the preparation of the threads a vatdyestuif and subjecting the same after the preparation of the threadshas been performed to a reduction process so as to form the leucocompound and to a subsequent oxidation process so as to regenerate thedyestuff.

3. In the process of preparing cuprammonium silk threads fromregenerated cellulose, the modification which comprises incorporatingwithin the solution serving as starting material for the preparation ofthe threads a vat dyestufi and subjecting the same after the preparationof the threads has been performed to a reduction process so as to formthe leuco compound and to a subsequent oxidation process so as toregenerate the dyestufi.

ROLAND RiiscH. HERMANN SCHMHDT.

